Several devices are available which use an electric motor to control the opening and closing of a door to a room. Devices are also available for which the opening or closing cycle can be initiated from a remote location using an infrared transmitter and the like such as disclosed in U.S. Pat. No. 5,040,331. Such door controlling devices must be constructed so as not to suffer damage when the device is not activated and the door is manually opened or closed. Similarly, it must be constructed so as not to suffer damage when an object such as a chair blocks the opening or closing of the door as the device operates through an opening or closing cycle.
Currently available door controlling devices utilize a slip clutch or the like which create a drag or resistance when the door is manually opened or closed. Furthermore, such slip clutches do not terminate the door opening or closing cycle when the movement of the door is interrupted by contract with an item such as a chair or a person's hand and, as a result, such devices apply a force against the obstruction until the operating cycle is completed. It is, therefore, desirable to provide a door controlling device which can be operated remotely to open and close a door, which will not create resistance when the door is not manually opened or closed, and for which the opening or closing cycle will terminate when the door encounters an obstruction which prevents completion of the opening or closing cycle.